On Aug. 15, Ben Affleck -- Oscar-winning wunderkind of Good Will Hunting, other half of "Bennifer," skyrocketing superstar who soared, sank and sizzled again thanks to his directing endeavors Gone Baby Gone and The Town -- turned 40.

He celebrated with a dinner party thrown by his wife, Jennifer Garner, at their Pacific Palisades home, attended by a handful of close friends on the brink of middle age, including Matt Damon, his WME agent Patrick Whitesell and Disney production president Sean Bailey.

"It was not fun for me," says Affleck of entering his fifth decade. "It's this moment of bifurcation between youth and middle age. One wants to think of oneself as young. One does not want to think: 'Wait a minute! How can I be halfway to death?' "

Halfway to death, perhaps, but sitting with him one late September morning at Santa Monica's Hotel Casa del Mar, this actor-turned-director -- the Hollywood embodiment of nine lives -- seems anything but as he bristles with nervous energy, words spilling out of him about his roller-coaster past and glittering present.

"He's gone to the top and then to the bottom and now to the top again," says Damon, his friend since the two met as children. "He's gotten the full measure of what this life in Hollywood can offer, and now he is comfortable with it."

Nearly a decade after Affleck had one of the most ignominious falls in Hollywood history -- thanks in part to Gigli and dubious PR stunts like kissing Jennifer Lopez's derriere in a music video -- he has emerged, unexpectedly and almost suddenly, as one of the best directors of his generation. Warner Bros.' Argo, an Iranian hostage drama that he helmed, is an early leader in the awards race. Set to open Oct. 12, it was called a "tight and tense political thriller" by THR's Todd McCarthy and has earned the kind of raves that once would have seemed impossible for the star of Armageddon.

All this is the hard-earned climax to a deeply considered shift Affleck embarked on eight years ago, when he set out his goals and determined never again to do work he was ashamed of. "I made the decision: 'I'm never, ever, ever going to do anything where I don't absolutely kill myself to get it right,' " he recalls.

Vanished is the man who dwelt on his deep insecurity when he and this reporter last sat down about five years ago. During that conversation, he admitted the Gone Baby Gone shoot had left him physically sick from stress. "I'm very insecure," he said. "I'm human, just like anybody else."

Vanished, too, is the tabloid pinata with his colorful love life, personal drama (including a stint in rehab) and career highs and lows. "I tried to ignore it as much as possible," he says of the fuss. "There was only one way to handle a situation like that: Go straight through it."

He addresses all this with an openness and even sweetness that would surprise those used to the more coiled figure onscreen. "I was shocked at how warm he is," says Alan Arkin, who plays a Hollywood producer in Argo. "He's got a great deal of warmth, and he's not afraid to show it. He has a wonderfully open, youthful quality that you don't see a lot in the characters he plays."

Sitting by a window overlooking the Pacific, in jeans and a blue-checkered shirt, unshaven and sipping from a plastic cup of soda, with flecks of gray in his beard and a gold tooth he's never bothered to replace, he has embraced the very doubts that once assailed him. "Anxiety is a kind of fuel that activates the fight-or-flight part of the brain in me," he says. "It makes sure that a velociraptor isn't around the corner and that you do as much as you possibly can to survive. Because Hollywood has a lot in common with Jurassic Park and its primeval-dinosaur universe."

Affleck, the one-time party boy, now gets up at 6, goes to bed at 9 and has been married for seven years with three children (Violet, Seraphina and Samuel) under age 7. As he discusses married life, Garner, about to fly to New York, calls on his cell.

"Hey, love, are you on the plane?" he asks gently. "I'm in an interview right now, but I love you very much." Then he quips that her trip is doubly traumatic for the actress, "First, 'cause she's away from the kids, second, 'cause I'm in charge."

She might have reason to worry, given how consumed Affleck is by work. "There are so many decisions to be made, and it's more than you can get to each day," he says. "There is this underlying anxiety not just about getting the movie done but getting it done really well. It keeps my head spinning -- even when I am giving the kids a bath. I can be giving them a bath or feeding them, and sometimes they say, 'Dad, pay attention!' "

When he's not with his family, he's at home working in a "sort of little office hut" or developing material through Pearl Street Productions, the Warners-based company he runs with Damon, who has remained a lodestar throughout the ups and downs and who now lives down the street from him. "We see each other almost too often," laughs Affleck. "I wonder if his wife is thinking, 'Is he really going to come over every night?' "

When he's on his own, he reads and consumes films avidly. He has just finished Laurence Gonzales' nonfiction book Surviving Survival, about how individuals cope with horrific incidents like being attacked by sharks; he also has been reading novelist Gillian Flynn's suspense drama Gone Girl and David Mitchell's Cloud Atlas.

Rather than watch television, he recently has immersed himself in a trip through some of the greatest films ever made -- from the 2011 Mexican movie Miss Bala to director Victor Fleming's The Wizard of Oz and Gone With the Wind, which he viewed back-to-back -- as if he wants to quench a raging thirst for the knowledge that will allow him to seize the ring within his grasp. He is intrigued to hear about MemoFrom David O. Selznick, a collection of the Gone With the Wind producer's notes, and orders it immediately by phone after his interview.

He also spends time at a coastal getaway near Savannah, Ga., and in his New York apartment, where he expects to move with Garner when their kids have grown up. He plays poker on a regular basis with actor Hank Azaria and his Argo producer Grant Heslov. "It's very, very psychological," he explains of his attraction to the game. "It's about weakness and strength and divining whether the other person is strong or weak."

He goes skeet shooting and admits to owning several guns -- which he has embraced since his wife faced a stalker.

"The stalker had been to our house many times and ultimately came to my children's school and was arrested," notes Affleck of Steven Burky, who was deemed insane in 2010 then placed in a mental ward and ordered to stay away from the Affleck family for 10 years. "It gave me a stronger sense of feeling protective about my family. There's a lot of crazy, weird people out there. It's an ugly world."

Affleck has given up any notion of reforming it. After once being rumored to want a career in public office, he now says, "I loathe politics." He supports President Obama but has not actively campaigned -- partly because of his workload, partly because of his political disillusionment and partly because he is convinced the president will win the election despite the Oct. 3 debate. "I watched it backstage at Jimmy Kimmel," he says. "It wasn't his best performance. But I am still going to vote for him, and I am very, very confident he will win."

As to his other interests: "Kids eat up that kind of hobby time," he admits. "I used to ride motorcycles. I used to play basketball. And now basically I'm at home with them, or I work."